(a) Field of the Invention
The invention relates to a long-acting formulation of biopharmaceutical, more specifically an aptamer therapeutics. A branch-type PEG or a hyaluronic acid (HA) derivative of which degradation in vivo is regulated is linked by the bioconjugation with biopharmaceutical. The new formulation of aptamer therapeutics improves the function of aptamer therapeutics and patient compliance, thereby improving quality of medical service.
(b) Description of the Related Art
Aptamers are nucleotide molecules having specific binding affinity to molecules through interactions other than classic Watson-Crick base pairing.
Aptamers, like peptides generated by phage display or monoclonal antibodies (“mAbs”), are capable of specifically binding to selected targets and modulating the target's activity, e.g., through binding aptamers may block their target's ability to function. Created by an in vitro selection process, called as systemic evolution of ligands by exponential enrichment (SELEX), from pools of random sequence oligonucleotides, aptamers have been generated for over 100 proteins including growth factors, transcription factors, enzymes, immunoglobulins, and receptors. A typical aptamer is 10-15 kDa in size (30-45 nucleotides), binds its target with sub-nanomolar affinity, and discriminates against closely related targets (e.g., aptamers will typically not bind to other proteins from the same gene family). A series of structural studies have shown that aptamers are capable of using the same types of binding interactions (e.g., hydrogen bonding, electrostatic complementarities, hydrophobic contacts, steric exclusion) that drive affinity and specificity in antibody-antigen complexes.
The first FDA-approved aptamer therapeutics of Macugen (pegaptanib) by Pfizer and Eyetech Co. in 2004 was a PEGylated vascular endothelial growth factor inhibitor for the treatment of age-related macular degeneration. It is reported that the risk of sightless person administered by Macugen® decreases to a half after the administration.
When the good aptamer therapeutics are administered parenterally in vivo, they are removed by the degradation with nuclease and by the rapid renal clearance in a few minutes. To overcome the short half-life, a chemical conjugation of the aptamer to poly-L-Lysine, polyamide, long chained alcohol, cholesterol and other steroids, phospholipid and peptide, etc. has been reported. In addition, PEG conjugation of the aptamer increases 10 times of half-life in vivo, and thus the aptamer can be used for therapeutically-active therapeutics. PEG includes a moiety of HO—(—CH2CH2O)n-H, and has been widely used for a long-acting formulation of biopharmaceutical.
It has been reported that an aptamer linked to two molecules of a 20 kDa PEG polymer in branch form has longer half-life than an aptamer linked by a 40 kDa PEG polymer, and thus has been used for most aptamer therapeutics (WO2006/029258).
PEGylation reagent where polyethylene glycol is linked to two amine residues of lysine via a peptide bond is commercially sold by Nektar. Urethane bond instead of the peptide bond in such product largely increases the stability of aptamer therapeutics (US 2003/0114647). Commercial PEGylated interferon of PEGASYS (trademark) produced by ROCHE is a PEGylated product with the branch-typed PEGlyation reagent sold by Nektar to largely increase bioavailability.